Aptasensor based on fluorescence resonance energy transfer for the determination of kanamycin

Based on fluorescence resonance energy transfer, an ultrasensitive aptasensor was designed to detect kanamycin. Carbon quantum dots (CQDs) connected to the 3′ end of the hairpin aptamer (HP) acted as energy donor, while gold nanoparticles (AuNPs) bound to the 5′ end of HP acted as energy acceptor. The interaction due to the overlapping between absorption spectrum of AuNPs and emission spectrum of CQDs led to an obvious quenching. After adding kanamycin, the specific binding between target and HP made the HP structure change. Then, the distance between CQDs and AuNPs increased gradually, and fluorescence intensity would recover. Therefore, the recovery of fluorescence intensity can be used for kanamycin detection via optical responses. Under optimal conditions, fluorescence intensity had a good linear relationship with the logarithm of kanamycin concentration. The detection limit of kanamycin was 5.7 pM (3.22 × 10 μg/kg) and the detection concentration of kanamycin concentration was 0.01–500 nM (5.65 × 10–282.80 μg/kg). The aptasensor was also applied into the determination of kanamycin residues in milk.